1. Field of the Invention
The present invention relates to a stereoscopic (3D) image display apparatus, a stereoscopic image capturing apparatus, and a stereoscopic image display method for displaying an image based on display data for allowing a viewer to perceive a stereoscopic image.
2. Description of the Related Art
Recently, a stereoscopic image technology that provides two images having horizontal parallax (binocular parallax) on a display so that a viewer may perceive the displayed images as a stereoscopic image of a subject has been highlighted. The two images used in the above technology are images captured from different optical axes (viewpoints), or images of computer graphics (CGs) corresponding to images captured at different optical axes. A location where a subject image included in the two images in a perspective direction is formed is determined according to a size of parallax between the two images of the subject.
As described above, the image forming location of the subject image in the perspective direction may be changed by adjusting the parallax between the two images of the subject. However, if the subject image is formed to excessively protrude or to excessively be recessed by having the parallax too large, the viewer may feel fatigue. Therefore, a producer (operator) who produces the two images processes image data obtained by an imaging operation or a CG producing operation into display data for allowing the viewer to perceive the stereoscopic image whenever the image data is generated, and displays an image based on the display data on a stereoscopic image display apparatus in order to check whether the size of parallax of the subject image is maintained within an appropriate range. However, in most cases, the producer has to determine the size of the parallax by using a scale on the stereoscopic image display apparatus, or based on experiences or intuition of the producer, and thus it takes a lot of efforts.
Thus, a technology of overlapping a guide functioning as a template with an image and allowing a person capturing the image to identify parallax between left image data and right image data has been suggested (Patent Document 1).
According to the Patent Document 1, since a guide is fixedly disposed, a subject image, in which parallax is to be derived, hardly overlaps with the fixed guide. Therefore, the producer has to estimate the parallax between images of the subject with naked eyes based on the guide that is separated from the subject image, and thus it is difficult to exactly determine whether the size of the parallax is maintained within an appropriate range. In addition, although the producer may determine whether there is parallax between images or not, it is difficult to observe visually a relative location of the subject image in a horizontal direction in display data that is obtained by composing two pieces of image data, and it cannot be determined whether the parallax is generated on a protrusion side or a recessed side. In addition, in a relatively small screen such as a small-sized monitor or a view finder, a reference for visually observing the parallax is not sufficient and thus it is very difficult to determine the parallax. As such, according to the parallax determination using naked eyes, the parallax may not be accurately defined, and moreover the producer has to spend a lot of time and effort to perform a comparison operation between the guide and the parallax.
Also, the producer briefly determines whether an image is adopted or not by displaying the image based on image data generated by an imaging operation or a CG producing operation, on a small-sized monitor or a view finder. However, the image data may be produced to be displayed on a large-sized screen of a theater. When sizes of display screens for displaying the display data are different from each other, parallax is also changed, and thus a stereoscopic effect in a small-sized monitor becomes different from a stereoscopic effect in a large-sized screen. Parallax in an arbitrary display screen may be estimated by multiplying a ratio of parallax with respect to a display width of the display data in a horizontal direction with a magnification (variation ratio) of the display screen. However, since the parallax of the display data is not determined accurately, estimation of parallax in an arbitrary display screen is not possible.
To address the above problems, the present invention provides a stereoscopic image display apparatus, a stereoscopic image capturing apparatus, and a stereoscopic image display method capable of allowing a producer to calculate parallax of each of subject images in display data easily and accurately.
(Patent Document 1) Japanese Laid-open Patent Publication No. 10-322725